TURNERS FALLS — After two hydraulic leaks since early 2022, FirstLight Hydro Generating Co. is planning an investigation into the Turners Falls dam’s bascule gate pistons.

A 1-gallon leak that occurred in March, as well as a 300-gallon leak in February 2022, have each been attributed to faults in four separate pistons. FirstLight, which owns the dam, has enacted “mitigation practices” in response, such as tightening up packing on the affected pistons, installing absorbent booms around each piston and regularly checking the booms to see if they need replacement, according to FirstLight Communications Manager Claire Belanger.

A more permanent solution could not immediately be pursued due to a variety of environmental conditions, such as an abundance of snow and ice and recent high flow rates in the Connecticut River.

“It was supposed to be addressed much earlier in the summer, but with the constant high waters, it’s not relatively feasible,” Town Administrator Steve Ellis informed the Selectboard on Monday.

“Flows in the Connecticut River have subsided to the point that yesterday, FirstLight was able to begin erecting the scaffolding required to conduct the detailed investigation of the Turners Falls Dam bascule gate pistons,” Belanger wrote in an email on Monday. “This investigation will inform our short- and long-term strategies to ensure that no further releases of hydraulic oil occur.”

Belanger detailed in her email that FirstLight is currently installing staging and safety handrails for worker protection. Installation of a support structure that will enable close investigation of the pistons and related piping will begin later this week.

“Once that installation is complete, we will begin the investigation and then implementation measures,” Belanger wrote. “Given this is a multi-step process and our ability to safely inspect is at the mercy of weather and river conditions, we cannot offer a definitive timeline, but we will continue to provide updates as each phase progresses.”

“The assessment … is whether it makes sense to remove or replace in kind or whether, in fact, a different approach needs to be implemented to avoid future failures of those hydraulic pistons,” Ellis explained to the Selectboard.

The hydraulic leak that occurred in February 2022 affected Pistons 7 and 8 below the fourth bascule gate. According to Len Greene, FirstLight’s head of government affairs and communications, material was able to be injected at these pistons to stop the leak that April.

The oil leak that occurred in March 2023 affected Piston 3 on the second bascule gate and Piston 5 on the third bascule gate. The adjacent absorbent booms, which were saturated as a result of the leak, were replaced shortly after the leak was observed to mitigate the issue.

After the March leak, local legislators implored FirstLight to rectify the situation “within the bounds of sound environmental practices.”

“After last year’s 300-gallon leak at FirstLight’s Turners Falls facility ... we spoke at length with FirstLight to ask what measures it was taking to both address the spill and to ensure its facility was in proper working order,” Sen. Jo Comerford, Rep. Susannah Whipps and Rep. Natalie Blais wrote in a joint statement in March. “But once again, we have another winter leak that threatens the health of the Connecticut River. And once again, FirstLight is promising vigilance. This time, and going forward, FirstLight must do better.”

At the time, there was no known cause for either leak, Belanger reported, noting that the upcoming investigation looks to rectify this.

“We will continue to provide updates as the investigation progresses,” Belanger wrote, “and we pivot toward determining the best permanent fix for this system and working on implementation.”

Reach Julian Mendoza at 413-930-4231 or jmendoza@recorder.com.

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